Method of treating rayon



Patented Feb. 24, 1931 PATENT OFFICE ARTHUR REILLY, OF WASHINGTON, DISTRICT OF COLUMBIA, ASSIGNOR TO THE TWITCHELL PROCESS COMPANY, OF ST. BERNARD, OHIO, A CORPORATION OI OHIO METHOD OF TREATING RAYON' No Drawing. Application filed July 10,

This invention relates to the manufacture of rayon and particularly to a method of protecting the rayon fibre between the time the fibre is constituted and the finished article is completed.

Rayon is the name now used to designate the many kinds of artificial silk which are at present upon the market and which fall, in general, under the headings of cellulose acetate, viscose, cuprammonia, and nitro silks. This process is applicable to all these types of rayon.

Between thetime the artificial rayon fibre is formed and the final product finished, the fibre is subjected to the physical wear of the various weaving and knitting processes and machines, to the moisture of the atmosphere when stored, to the rubbing and abrasing incidental to the washing and dyeing processes, to the chemical ingredients of the wash waters, to the alkalinity of the soaps used in the washing operations, and when piled for storage to the weight of the material above. which tends to cause the fibres to adhere to one another.

Rayon is a relatively delicate fibre and has not the resistance of most natural fibres to the physical or chemical conditions to which it is subjected in the fabricating processes. All elements, therefore, which are brought into contact with the rayon, during its process of fabrication, must be carefully scrutinized to avoid all substances and ingredients which might have harmful actions on the rayon, or which might secondarily produce conditions undesirable for the rayon.

The theory underlying this invention is that it is undesirable to treat the rayon with fatty substances, vegetable or animal oils, soaps, and the like, to any extent more thanl positively necessary, for the reason, that the animal and vegetable oils as a class are not appropriately chemicallyinert in regard to oxidation and other reactions, that in the presence of water the soaps of said substances tend to produce alkalies by hydrolysis, which is bad for the rayon, that said substances tend to form insoluble components dilficult to remove from the rayon, which results in unevenness 1n dyeing, etc., unless the rayon is 1929. Serial No. 377,342.

subjected to such severe washing that its strength is weakened.

According to this invention, it is possible to apply a protective coating to the rayon Which will lubricate the same for weaving or knitting, which keeps out excessive moisture, which permits storage without adhesion of the fibres, and which can be removed readily and whenever desirable without the use of any fatty substances of soaps. The particular class or materials which afford these utilities also have the advantage that they can be applied to the rayon either directly without moisture present or in the form of a permanent aqueous emulsion devoid of hydrolizing components or any fatty substances of the class heretofore criticized.

These materials adapted to be used in this method of treating rayon comprise essentially admixtures of chemically inert, stable and neutral mineral oils, such as parafiine oil,

though a light colored technical oil is pref-- erably used with or Without aromatic, chlorinated solvents or low viscosity mineral oil spirits, and mahogany sulphonates devoid of the oil entrained in the sulphonating process. The absence of the entrained oil makes available the true emulsifying power of these mahogany sulphonates, which their remixture with oil does not lower.

In other words, when these mahogany sulphonates are formed by the fuming sulphuric acid treatment of lubricating stocks to form light colored technical oils or medicinal white oils according to the Petrotf-Humphries process, certain components of the oil treated, adhere tenaciously to the sulphonates and are removed with them from the batch, leaving the white oil or light colored technical oil as a remainder.

The material removed, that is, the mahogany sulphonates plus the entrained oil, con-- stitutes the ordinary mahogany sulphonates of commerce. This material in its acid phase is known as kontact both in this country and abroad, and is used in the splitting of fats. When, however, these entrained oils, or oils having a great affinity for the sulp'honates, are separated from the sulphonates, for

instance, by treatments with high proof alcohol, the sulphonates change in physical and chemical properties to such an extent that they are, for all practical purposes, a different substance from what they were with the entrained oil present.

Now, if this true mahogany, as distinguished from the mahogany soap ofcommerce, is mixed with a neutral mineral oil, such as a light colored technical oil, a product results which has, as far as rayon is concerned, the lubricating and protective value of the true mineral oil and the water soluble properties of the sulphonates somewhat accentuated, since the peculiar paradox exists that while mineral oil will not mix with water and mahogany sulphonates can be dissolved in water only with difliculty, their combination is highly water soluble.

If the ordinary mahogany sodium sulphonate of commerce is mixed with a mineral oil, permanent emulsions cannot be obtained without the use of fatty substances, rosins, ordinary soaps, alcohols, acetones, or other stabilizing or blending agents, but if the true mahogany be used one is able to omit the use of any of these materials considered detrimental primarily or secondarily to the rayon.

Furthermore, the admixture or combination of true mahogany and mineral oil is so water soluble that it may be readily removed from the rayon at any time desired during the process of fabrication without the customary severe scouring with fatty acid soaps, or the like, and the abrasion and chemical action incidental thereto.

While the percentage of these two components can be varied within wide limits, between and true mahogany is desirable from the point of view of readily removing the protective coating from the rayon by immersion in water, and 2 true mahogany is suflicient to produce with mineral oils a protective coating which can be removed without appreciable damage to the rayon.

A further advantage ofthe use of the protective coatings above described is that they can be applied and removed without the use of temperatures sufficiently high to damage the rayon. Another advantage of the use of these materials on rayon is that the protective coating is more inclined to film on the rayon than are ordinary oils, which, in the first place, insures complete protection of the rayon fibre, and in the second place, complete protection with a minimum of material.

Having described my invention, I claim:

1. The method of protecting rayon fibres between the time of their formation and the completion of the article of rayon, comprising, forming a coating on said rayon fibre of chemically inert mineral oil and true mahogany.

2. A method of treating rayon, which comprises, forming a film of inert mineral oil and true mahogany on the rayon fibre prior to the weaving or knitting operations, and removing said film by immersion in water prior to the dyeing or finishing operations.

3. A method of treating rayon, which comprises, forming on the rayon a protective film of mineral oil and true mahogany, said film devoid of any substantial quantity of fatty substances, and later removing said film from the rayon in an aqueous bath devoid of any appreciable quantity of fatty substances.

4. In the process of manufacturing rayon articles, the step of coacting the rayon fibre with a protective film, comprising, mineral oil and true mahogany.

5. In the process of manufacturing rayon articles, the step of coating the rayon fibre with a. protective film, comprising, mineral oil and true mahogany, and the step of later removing said film in an aqueous bath devoid of substances tending to form insoluble bodies in the bath.

In witness whereof, I hereunto subscribe my name.

ARTHUR REILLY. 

